<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .div {
            width: 200px;
            height: 200px;
            background-color: gold;
            border-radius: 40px;
        }
    </style>

    <script src="../node_modules/jquery/dist/jquery.js"></script>
    <script>

        $(() => {
            $('#sss').click(() => {

                $('.div').slideToggle(100, () => {
                })
            })
        })
    </script>
</head>

<body>
    <input type="button" value="ojbk" id="sss">
    <div class="div"></div>

</body>

</html>